The present invention relates to the winding of yarn on reels or packages in textile machines for the preparation of yarn, and in particular relates to a device with a reel-stick arm supporting the rotating tube on which the reel of yarn is formed.
In industrial practice, a solution that has met with considerable success is that of actuating the tube in rotationxe2x80x94with the reel that is formed by winding the yarn on its surface which has the shape of a truncated cone or cylinderxe2x80x94by driving the said tube in rotation with an underlying motor-driven roller on which the reel itself rests, thus enabling winding of the yarn at a constant linear speed that is independent of the size of the reel, which grows as the winding operation proceeds, and dependent only upon the speed of rotation of the said actuating roller. The yarn is wound in turns on the reel and distributed with a to-and-fro motion over its generatrix by a traversing device.
A problem linked to the winding of yarn of a reel resting on its actuating roller is due to the fact that the reel, as it grows, exerts an ever-increasing weight and applies an ever-increasing pressure on the roller, with consequences on the progress of the operation and on the mechanical and geometrical characteristics of the reel produced. For instance, the reel itself becomes more and more deformed at its point of resting as it grows. As a result, both the tension of the turns of yarn and the density of the wound layer increase. As the pressure exerted varies, the transmissible torque, especially in the speed transients, varies noticeably, and the possibility of mutual friction increases.
In order to highlight more clearly the technical problems tackled and solved by the present invention, as well as the characteristics and advantages of the invention with respect to the prior art, the said invention is here described with reference to its application in gathering units for yarn produced on double-twist twisting frames by winding it in reels, even though the device according to the invention may also find application in the entire range of machines for preparing and finishing yarn in which the yarn is wound in reels. Consequently, application of the invention is not at all intended to be limited to twisting frames alone.